Electrodynamics in particle physics

[ghery]

Hi:

I've heard that in electromagnetism, there is a system of units called Lorentz - Heaviside system, and that in particle physics, tis system is used insted of the gaussian or the SI. Why do particle physicist use this system? and by the way, How do we go from the Gaussian system to the Lorentz-Heaviside system?

Thanks a lot for your support

 

[Meir Achuz]

Unfortunately particle physicists seem to use Gaussian and L-H in roughly equal numbers,
although I think (and hope) that Gaussian is winning more recent favor.
Fortunately, I know of no HEPist who uses SI, except to confuse undergraduates.
Heaviside "rationalized" that dividing e^2 by 4pi would make some equations simpler. The same confusion is introduced in SI. All you have to do to go from Gaussian to H-L is divide e^2 by 4 pi. The good news is that alpha is the same in all known systems. In Gaussian, alpha=e^2=1/137. In H-L, alpha=e^2/4pi=1/137.
Be careful in reading any paper or book because some authors don't state clearly which system they are using.

 

[sir-pinski]

.

Electrodynamics in particle physics is a fascinating topic that explores the fundamental interactions between particles and electromagnetic fields. As you mentioned, particle physicists use the Lorentz-Heaviside system of units instead of the Gaussian or SI systems. This is because the Lorentz-Heaviside system is more convenient and consistent for describing the dynamics of particles moving at high speeds, which is a common occurrence in particle physics experiments.

The Lorentz-Heaviside system is based on the concept of natural units, where fundamental physical constants such as the speed of light and the Planck constant are set to 1. This simplifies equations and eliminates the need for conversion factors, making calculations more efficient. Additionally, the Lorentz-Heaviside system is closely related to the relativistic nature of particle physics, making it a more suitable system for this field of study.

To convert from the Gaussian system to the Lorentz-Heaviside system, one can use the following equations:

- Electric field: E_L = E_G/√(4πε_0)
- Magnetic field: B_L = B_G/√(4πμ_0)
- Electric potential: φ_L = φ_G/√(4πε_0)
- Electric charge: q_L = q_G/√(4πε_0)
- Electric current: I_L = I_G/√(4πε_0)

Where E_L and B_L are the electric and magnetic fields in the Lorentz-Heaviside system, E_G and B_G are the electric and magnetic fields in the Gaussian system, and ε_0 and μ_0 are the permittivity and permeability of free space, respectively. Similarly, φ_L, q_L, and I_L represent the electric potential, charge, and current in the Lorentz-Heaviside system, while φ_G, q_G, and I_G represent the same quantities in the Gaussian system.

In conclusion, the Lorentz-Heaviside system of units is widely used in particle physics due to its convenience and compatibility with the relativistic nature of this field. Its conversion from the Gaussian system is straightforward and allows for more efficient calculations and descriptions of particle interactions. I hope this explanation helps clarify the use of the Lorentz-Heaviside system in particle physics.